Stencil sheet for use in duplicating



Patented Jan. 28, 1930 UNITED STATES PATENT OFFICE ABMAND DE WAELE, OF LONDON, ENGLAND, ASSIGNOR TO D. GESTETNER, LIMITED,

OF LONDON, ENGLAND STENCIL SHEET FOR USE IN DU PLICATING No Drawing. Application filed July 6, 1927, Serial No. 203,872, and in Great Britain July 8, 1926.

i use in duplicating.

In the production of stencil sheets for use 111 duplicating, compositions contalnlng oleaginous materials are commonly used in forming the inkresisting medium of the stencil or, in other words, the coating composition which is supported by the highly porous material such as yoshino paper. A

a typewriter and as is well known the platen of the typewriter is formed of rubber as also are the feed rollers associated with the platen.

Oleaginous material's generally, for instance mineral oils, and the majority of fatty oils cause bodies of rubber to swell irregularly and inconveniences have arisen owing to the oleaginous materials included in such compositions detrimentally affecting the rubber portions of the typewriter with which they come into conta Itwould appear that castor oil exerts no or little detrimental action upon rubber and consequently the use of this oil in the production of stencil sheets would appear desirable. u

WVith certain of the coating compositions which are at present in use, notably with the gelatineoil compositions employed in the production of stencil sheets of the character which do not need moistening prior to cutting the stencil'and whlch do not .rely for. their sensitivity upon their content of moisturc, it isfound diflicult, if not impossible, to use castor oil as the sole or main tempering or softening agent for the gelatinizing organic colloid. 1

With regard to stencil sheets of this character it may be stated that the coating composition thereof consists of a gel in which is dispersed a non-hygroscopic and substantially non-water-retaining material acting as the sole or main tempering or softening agent for the gel and functioning to enable the structure of the composition to be broken down by the blows of the elevated portions of the type faces of atypewriter or by the pressure applied by means of a style without'the areas enclosedby the incisions thus formed becomand a higher hydroxy fatty acid ester of a ing detached from the remainder of the stencil sheet, such stencil sheets being commonly known as dry or permanent stencil sheets. The present invention is based upon the observation that the higher hydroxy fatty acid esters of alcohols which contain one or, at most, two hydroxy fatty acid radicles to each alcohol radicle 1n the ester molecule do The majority of stencil sheets are employed in the production of stencils with the aid of ticularly upon the observation that the esters 5 p of the higher hydroxy fatty acids and-particularly the ricinoleic acid or poly-ricinoleic acid esters of the monoor di-hydroxy alcohols or mixtures thereof are suitable for use in the production of stencil sheets of the character above indicated. 1 The invention therefore consists broadly in stencil sheets the coating compositions of,

Which-include a gelatinizing organic colloid Y.

alcohol, containing one or, at most, two'h droxy fatty acid radicles to each alcohol radi cle in the ester molecule.

' The invention more particularlyliionsists in stencil sheets the coating compositions "of so which include a gelatinizing organic colloid and a higher hydroxy fatty acid ester of a monoor di-hydric alcohol.

, Thus, in accordance with the invention, a stencil sheet may comprise a coating composition including a gelatinizingorganic colloid dispersable in water in association with a higher hydroxy fatty acid ester of a monoor di-hydric alcohol and optionally with an emulsifying agent.

The hydroxy fattyacid esters of the glycols may conveniently be used in accordance with the invention; for instance the ricinoleic acid ester of ethylene glycol or trimethylene glycol may be employe I L As an example of an ester of a mono-hydric alcohol the ricinoleic acid-ester of ethyl alcohol ma be mentioned.

The f0 lowing particulars are given by way of illustration of suitable manners of carrying the invention into efiect':

Ewample I A compositionincluding the following ingredients in'the' proportions stated:

Parts by x weiht. Sulphon'ated sperm oil flii Trimetliylene glycol ri cinol"eate '66 Distilled Water; 50 Titanium pigment 15 Bentonite or wilkinite 3 is prepared andjis added to a dispersion of 14 parts by weight of gelatine in 200 to 300 j part'sby Weight of distilled water with which it is thoroughly mixed. Sheets of yoshino paper are coated with this mixture in known nianner and after the gelatinous composition has set the coated sheets are subjected to the action of formaldehyde vapour.

Example a A composition including the following in gredients in the proportions stated Parts by weight Sulphonated sperm oil Trimethylene glycol ricinoleate .66 Distilled water. Titanium pigment; 15. Bentonite or wilkinite 3 is prepared and is added to a dispersion of 11 parts by weight of gelatine in 200 to 300 parts by weight.o f distilled water. With this composition sheets of yoshino paper are 'coated and impregnated and treated with formaldehyde in known manner.

As will be understood, a very large number of bodies fall within the scope of the broad definitions of the invention which are given above and it has not yet been possible to prepare or obtain bodies fully representative of this class.

It is essential that the softening material or tem ering agent in the coating compositiqns s all possess a. relatively low degree of viscosity and itmay be that the esters of some of the higher mono-hydric alcohols or glycols will themselves be too viscous; these are to be regarded as excluded from the scope of the invention, at least in so far as it is concerned with the production of stencil sheets with the aid of aqueous disperse systerns including gelatinizing organic colloids j dispersable in water and an ester of the character specified as the main tempering'agent.

In conclusion it is to be observed that the expresslon higher hydroxy fatty acid as used herein iineans hydroxy fatty acids havinga number of carbon atoms in their molecules not less-than; six and more especially such acids as have a number of carbon atoms in the neighbourhood of 16 to 18.,

11. Stencil sheets (for use in duplicating,

Having now described my invention, what I claim as new and desire to secure by Letters Patent is 1. Stencil sheets for use in duplicating, the

coating compositions of which include a gelatinizing organic colloid and a higher hydroxy fatty acid ester of a di-hydric alcohol.

2. vStencil sheets for use in duplicating, the

coating compositions of which include a gelatinizing organic colloid and a higher hydroxy fatty acid ester of a'glycol.

3. Stencil sheetsfor use in duplicating,

- the coating compositions of which include a gelatinizing organic colloid and a ricinoleic 1 acid ester of a glycol as tempering agent.

4. Stencil sheets adapted to be stencilized by pressure in asubstantially air-dry state comprising an ink-resisting coating which includes a gelatinizing organic colloid and a ricinoleic acid ester of a glycol.

'5. Stencil sheets for use in duplicating, the coating compositions of which include a gelatinized proteinand a higher hydroxy fatty acid esterof a di-hydric alcohol.

6. Stencil sheets for use in duplicating, the coating compositions of which include a gelatinized protein and a higher hydroxyl atty acid ester of a glycol.

7. Stencil sheets for use in duplicating,

the coating'compositions of which include a I gelatine and a ricinoleic acid ester of a glycol gelatinizing organic colloid and a ricinoleic acid ester of an alcohol containing not more than two hydroxyl groups.

the coating compositions of which include a gelatine and a ricinoleic acid ester of an alcohol containing not more than two hydroxyl groups.

12. A stencil sheet for use in duplicating comprising a coating composition including a -gelatinizing organic colloid dispersable in water in association with an ester of a higher hydroxy fatty acid containing'not more than two hydroxy fatty acid radicles in the ester molecule. In testimony whereof I have signed my name to this specification.

ABMAND DEwAEL-Ej 

